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Thread: Sealing a sprayed sunburst

  1. #1
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    Default Sealing a sprayed sunburst

    I have finished the sunburst on my GOM and am wondering if I should seal it with shellac or will the alcohol in the shellac cause the dye to blotch or run. The dye was mixed with a 1lb cut of shellac for application. I am planning nitro lacquer for the finish coating.
    Bob Schmidt

  2. #2
    Registered User sunburst's Avatar
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    Default Re: Sealing a sprayed sunburst

    A light spray of shellac will not affect the dyes, but if the sprayed coat is the least bit too wet the dyes can move.

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  4. #3

    Default Re: Sealing a sprayed sunburst

    I'd love to see pictures of your GOM build.

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    Default Re: Sealing a sprayed sunburst

    Thanks John. This was my third attempt and I hope the last for this top. When I took the tape off of the sides of the fretboard it exposed some dye differences I have to try to patch. If that does not work I will be on attempt 4.
    I will post pictures as soon as I can get some lacquer on them. It's been tough to find a weather window to spray them.
    Bob Schmidt

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    Default Re: Sealing a sprayed sunburst

    Hi. Can I message you ? I would like to know what you are using, and pictures. That okay? Are the dyes water based or chemical? The shellac that your using , will it act as a sealer? Or will it go south on you when you apply nitro? Have you done a test panel prior to doing your instrument to see if these will all work together?

    Reason I ask you. Is I would like to get into finish work on these. I am a auto painter by trade. Guitars or Musical instruments would be new to me.

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    Default Re: Sealing a sprayed sunburst

    slimt - yes, no problem. I just finished the sunburst last night (attempt number 4) so it is ready for lacquer. As you can tell by my question, I am still a novice at this, but as you can see from John's response there are several experts on the forum who are willing to answer questions about the process. There are also some very good threads on the subject of finishing and sunbursting.
    To answer your questions, the dyes I am using are sold by stumac. They are true dyes and not pigments so they do penetrate the wood. That is why I first sealed the spruce with shellac, and chose to air brush it since it would give me better control. I did hand rub the maple back and sides, but they are not sunbursted. The dyes will mix with water, alcohol or lacquer.
    My understanding is that shellac is a good sealer under nitro. I did test until I ran out of scraps but that was primarily to get a color match with the backs and sides. I did discover that I could ruin the sunburst with a wet coat of shellac on one of my failed attempts which is what prompted this question. I have not tested with nitro yet since spraying conditions have been much less then ideal. I put a couple of coats of 1lb cut shellac over the finish with the air brush last night and I may get a chance to start the lacquer today.
    I was planning to post pictures when I am finished. Feel free to PM me or post to this thread if you have any other questions, and as I said there are several people on the forum who have a lot of knowledge on this process and are willing to answer questions.
    Bob Schmidt

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    Registered User sunburst's Avatar
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    Default Re: Sealing a sprayed sunburst

    Keep your layer of shellac sealer as thin as you can. I've never had problems with very thin shellac sealer coats under lacquer, but thicker shellac coats can cause problems with lacquer. I usually spray 2 barely perceptible coats of shellac as a sealer and then give it a very light rub with 320 grit sandpaper right before spraying lacquer.

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  12. #8
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    Default Re: Sealing a sprayed sunburst

    I will just add that shellac sealer is NOT compatible with Cardinal lacquer, though it seems to be fine with other lacquers. Cardinal seems to cause the shellac to release from the wood, causing areas of delamination.

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    Default Re: Sealing a sprayed sunburst

    Thanks for the heads up. So it is light 320 sanding and off to lacquer. I do have a thin coat of shellac on it now.
    Bob Schmidt

  15. #10

    Default Re: Sealing a sprayed sunburst

    I seal spruce with very light coats of super blonde shellac like sunburst. I also have had good success with hand rubbed/blended sunbursting using Transtint in an alcohol medium over a shellac sealed top. I usually resort to spraying if I want that very dark tinting around the rim.

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